Thioethers of molecular weight 258.39



United States Patent 3,102,917 THIOETHERS OF MOLECULAR WEIGHT 258.39Walter Reifschneider, Midland, Mich, assignor to The Dow ChemicalCompany, Midland, Mich, a corporation of Delaware N0 Drawing. Filed June27, 1962, Ser. No. 205,513 3 Claims. (Cl. 260-609) The present inventionis directed to thioethers and in particular is directed to novelthioethers having a molecular weight of 258.39, within a tolerance oferror of 0.01, and corresponding to the formula Sig i wherein Xrepresents halogen, and a benzenethiol corresponding to the formulawherein one G is hydroxyl and the other is hydrogen; and one R istert.-butyl and the other is hydrogen. During the reaction to preparethe present compounds, one molecule of thiol reacts with each moleculeof aroma-tic halide. When it is desired to prepare the present compoundin a high state of purity and with a minimum of post-synthesispurification procedure, the starting reactants should be employed inequimolecular proportions, or with the vthiol in slight excess. However,other proportions may be employed if desired, and unconsumed startingmaterial of whatever identity may, if desired, be recycled into furthersynthesis process.

The reaction goes forward at temperatures over a Wide range such as 20to 350 C., but initiates most readily when heated to a temperaturesomewhat higher than room temperature; 100 to 250 C. is a preferredrange. Under these conditions the reaction is, in general, exothermicand goes forward to completion with good yield calculated upon the basisof consumed starting material. Hydrogen halide of reaction is evolvedand means :for its orderly disposal are advantageously provided.

Typically, in the preparation of the compounds of the present invention,reaction between the thiol starting material and the aromatic halidestarting material will initiate and go forward only when there isemployed a catalytic amount of both a source of cuprous ion and anitrogenous base. Thus, in the preparation of several and probably allof the present compounds, the employment of such catalyst is essentialand critical, although the exact weight is not critical. Certainly, theemployment of such catalyst is in all cases highly advantageous. The

3,102,91 7 Patented Sept. 3, 1 963 "Ice source of cuprous ion may bemetallic copper, in which case the copper reacts in some way to obtainouprous halide. Also, cuprous oxide may be employed as a source ofcuprous ion in which case water of reaction is evolved and cuproushalide results. Cuprous chloride itself or other cuprous salt may beemployed. The employed weight is not critical, but may vary from a verysmall trace amount, less than i of 1 molar percent, to as much as anamount equi-molecular with either -1e actant or even greater. Ingeneral, the employment of larger amounts is accompanied by no majoradvantage and, being expensive, is not preferred.

The nitrogenous base may be ammonia, a primary, secondary, or tertiaryaliphatic or aromatic amine or a nitrogenous heterocycle wherein thenitrogen acts, or is capable of acting, as a basic substance. Ifdesired, the nitrogenous base may be a naturally liquid substance whichis employed as a reaction medium. Otherwise, such-base is dissolved ininert liquid reaction medium such as an aromatic or aliphatichydrocarbon oil.

In laboratory preparations, it is preferred to employ a liquidnitrogenous base catalyst substance in suificient excess that portionsof it may act as solvent, portions may act as hydrogen halide acceptorand yet iurther portions may continue to function, unreacted, in the:necessary catalytic manner.

In carrying out the reaction to prepare the compounds of the presentinvention, the aromatic halide and the thiol are intimately mixed andblended, in any order and in desired amounts, with source of cuprous ionand nitrogenous base as hereinbefore described, and thereafter heated toa temperature at which reaction takes place promptly. In one convenientmethod the reaction temperature may be the reflux temperature of theliquid reaction mixture. In this situation, heating may be continued atthe boiling temperature of the reaction mixture and under reflux for aperiod of time to carry the reaction to completion.

Upon completion of the reaction, the desired compounds of the presentinvention are separated in manners which, in view of the teaching of theinstant specification, will be evident to skilled chemists. In one suchmanner, the reaction mixture, hot from heating to the reactiontemperature, is poured into a mixture of ice and concentratedhydrochloric acid whereupon a precipitate forms from which the desiredproduct can be extracted as a solvent-soluble fraction. Representativeextraction solvents include diethyl ether, chlorinated hydrocarbons, andbenzene. In any event, the product is extracted with solvent, thesolvent extract dried over an inert drying agent such as, for example,anhydrous sodium sulfate or the like; the solvent vaporized and removedand the remaining product distilled; or it may be chilled or otherwiseinduced to crystallize and, if desired, recrystallized from a solventsuch \as -a lower alkanol.

When production of the present compounds is to be carried out on anindustrial scale, various other methods of separation and purificationmay be preferred, including, for example, centrifugation, decantation,vacuum distillation, and the like.

The following examples, without more, will enable those skilled ExampleI.4-Tertiarybutyl-2-(Phenylrhi0)Phen0l A reaction mixture is prepared,consisting of 18.3 grams (0.1 mole) of 2-chloro-4-tertiarybutylphenol,16 grams of cuprous oxide (technical grade) and 11 grams (approximately0.1 mole) of 'benzenethiol dispersed in a mixture consisting ofmilliliters quinoline and 10 milliliters lutidine. The resultingreaction mixture is placed in a flask under reflux, the reflux beingequipped with a water trap. in this situation, the reaction mixture isheated at its reflux temperature (a pot temperature in the art topractice the present invention.

between approximately 200 and 240 C.) for 6 hours to carry the reactionto completion. At the end of this reaction period, the resulting hotmixture is poured into a mixture of shaved ice and excess concentratedhydrochloric acid. As a result of these procedures, the ice melts andbasic substances react with hydrochloric acid; in the resultingacidified water a precipitate forms. The precipitate is collected byfiltration and extracted with ether, the ether extract liquid beingsaved. This liquid is dried :over a bed of anhydrous sodium sulfatewhich also neutralizes remaining traces of acidic substances; the

resulting liquid is warmed to vaporize and remove ether solvent andobtain a residual oil. This oil crystallizes upon standing; the crystalsare taken up in hot ethanol and precipitated therefrom as the ethanolcools, to obtain a 4- -butyl-2-(phenylthio)phenol as White crystalsmelting at 73.5 -75.5 C.

The use of a thorough wetting spray containing, as sole protectiveagent, 75 parts of the compound of the present example per million partsby Weight of resulting aqueous spray proved quite eifeotive in theprotection of young tomato plants from subsequent infestation with alive culture of spores of Fusarium wilt, whereas untreated check plantswere seriously infected.

The compound is also a selective herbicide.

Example II.-(p-t-Butylphenyl-Thio)Phenol In procedures essentiallysimilar to the foregoing exa l cept that the starting thiol was a p-tbutylbenzene-thiol and the aromatic halide was o-chlorophenol, there isprepared, in good yield, o-(p-t butylphenyl-thio)phenol as a colorlessliquid punified by vacuum distillation. lhe product boils at l-177 C.under absolute pressure of 3 millimeters mercury. The compound was quiteeffective when employed in Water at a concentration of ten parts permillion as a piscicide. It is also a fungicide, insecticide, andselective herbicide.

The other compounds are readily prepared in good yield in other similarpreparations.

I claim:

1. A compound corresponding to the fonrnula 2. 4-tertiarybutyl-2(phenylthio)phenol. 3 0- (p-tertiarybutylphenylthio phenol.

No references cited.

1. A COMPOUND CORRESPONDING TO THE FORMULA